Persistent echo on incoming calls

[victor.rosa]

CSCsd54344 Bug "DSP: Persistent echo heard on c5510 DSPs with 4.4.13 DSPware or higher", was identified on Cisco 2801/2811/2821/2851/3825/3845 with PVDM2 DSP.

We have a 2821, IOS version 12.4(20)T2 with DSP Type C5510 and, DSPWARE Version 23.8.0 with a similar issue.

The question is if this bug applies to the DSPWare version we are running?

Please advise

[testeven]

Hi Victor,

The bug does not list all the DSPware versions affected, but I've seen it

was fixed in DSP firmware 8.4.0.

Could you try rebooting the router and see if the issue goes away?

Regards,

Tere.

If you find this post helpful, please rate!

[victor.rosa]

Have tried several times...

[Gregory Garrian]

One way to see if a certain code is affected is to look at the ECAN library for the dspware via the

'show call active voice echo-canceller port x/y:z" command.  If it shows ecan library 9.175, then that

dspware is susceptible to this bug. 

Example:

Gateweay#show voice call status

CallID     CID  ccVdb      Port        DSP/Ch  Called #   Codec    Dial-peers

0x2        120F 0x65FBAD60 2/1:23.1    2/1:1  *111111    g711ulaw 1/9913173

1 active call found

Gateway#show call active voice echo-canceller 0x2   

ACOM=32  ERL=20

Echo canceller control words=6C 1801

Bypass=OFF  Tail=64  Residual ecan=Comfort noise

Freeze=OFF  Modem tone disable=Ignore 2100Hz tone

Worst ERL=6  High level compensation=OFF

Max amplitude reflector (in msec)=18

Ecan version = 9175

[victor.rosa]

ACOM=11  ERL=11

Echo canceller control words=60 1000

Bypass=OFF  Tail=24  Residual ecan=Comfort noise

Freeze=OFF  Modem tone disable=Ignore 2100Hz tone

Worst ERL=6  High level compensation=OFF

Max amplitude reflector (in msec)=3

Ecan version = 9177  <====

This then means we should be OK?

[Gregory Garrian]

I believe so.  That being said, that's some a pretty old IOS to be running.  Is upgrading the IOS an option?  Even to 124-24T3 would eliminate the bug as a cause of the issue.

[victor.rosa]

Will verify, and advise.

Thanks